CODEWITHSUNDEEP
sql-serverdatabasealgorithmdata-structurestree
Ian Ringrose
Ian Ringrose

Reputation: 51927

What is a Bw-tree?

I have just read a paper on "in memory OLTP" for the next version of SQL server; it mentions BW-Tree as being added as well as hash indexes in CTP2.

So what is a BW-Tree? Can someone explain a bit about it without me (and everyone else) having to read a 12 page research paper.

Upvotes: 16

Views: 6950

Answers (2)

Jos de Bruijn - MSFT
Jos de Bruijn - MSFT

Reputation: 424

In a nutshell, a bw-tree is a kind of b-tree that is optimized for in-memory and for high concurrency.
For in-memory: the pages are variable-size and always tightly packed; there are no partially-filled pages
For high-concurrency: the data structure is completely latch- and lock-free to support concurrent DML without blocking.

Upvotes: 19

ngneema
ngneema

Reputation: 444

From Microsoft:

Our new form of B tree, called the Bw-tree achieves its very high performance via a latch-free approach that effectively exploits the processor caches of modern multi-core chips. Our storage manager uses a unique form of log structuring that blurs the distinction between a page and a record store and works well with flash storage.

You can read the PDF Here

Upvotes: 11

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